Geobacter

Geobacter is a genus of Gram-negative, anaerobic, non-fermentative bacteria that are known for their role in bioremediation, bioenergy, and microbial fuel cells. Geobacter species have the unique ability to transfer electrons to metals and other solid substrates, a process known as extracellular electron transfer (EET), which is central to their environmental significance and application in technology.

Characteristics

Geobacter species are typically rod-shaped and possess flagella, which allow them to move in aqueous environments. They are distinguished by their capability to oxidize organic compounds completely to carbon dioxide in the absence of oxygen, using iron (Fe(III)) or other metals as the terminal electron acceptors. This metabolic capability enables Geobacter to play a crucial role in the biogeochemical cycling of iron and other metals.

Ecology

Geobacter species are widely distributed in a variety of environments, including soils, sediments, and subsurface environments contaminated with organic pollutants or heavy metals. They contribute to the natural process of biogeochemical cycling by participating in the reduction of iron, manganese, uranium, and other metals. This activity can influence the mobility and bioavailability of these metals, with significant implications for environmental health and remediation efforts.

Applications

Bioremediation

Geobacter species are of particular interest in the field of bioremediation due to their ability to degrade organic pollutants, such as petroleum hydrocarbons, in anaerobic conditions, and to immobilize heavy metals like uranium and chromium by reducing them to less soluble forms. This makes them valuable allies in cleaning up contaminated groundwater and soil.

Bioenergy

In the context of bioenergy, Geobacter species have been explored for their potential in microbial fuel cells (MFCs), where they can generate electricity from the oxidation of organic compounds. Their unique extracellular electron transfer capabilities allow them to directly interact with electrodes, facilitating the conversion of chemical energy into electrical energy.

Research

Ongoing research into Geobacter includes understanding the mechanisms of extracellular electron transfer, optimizing their use in microbial fuel cells and bioremediation, and exploring their potential in other applications such as biomineralization and the production of bio-based materials.

See also

• Bioremediation
• Microbial fuel cell
• Extracellular electron transfer
• Biogeochemical cycle